Traveling grate stoker including



June 20, 1950 E. MIDGETTE Erm.

TRAVELING GRATE STOKER INCLUDING GRATE BAR RETAINING MEANS 6 Sheets-Sheet 1 Filed Jan. 51, 1946 June "2 0, 1950 Filed Jan. 31, 1946 E. L. MIDGET-'rE .l-:TAL mvELING Gam: s'roxER INCLUDING GRATE BAR RETAINING mms l 6 SheetsSheet 2 June 20, 1950 E. l... MIDGETTE Erm.'

TRAVELINGGRATE STOKER INCLUDING GRATE BAR RETAINING MEANS 6 Sheets-Sheet 3 Filed Jan. 31, 1946 June 20, 1950 E. L. MIDGr-:TrE ETAL f TRAVELING GRATE s'roxz-:R IncLunmc GRATE BAR RETAINING MEANS Filed Jan. 51, 1946 l e sheds-'sheet -4 June 20, 1950 E. L. MIDGETTE l-:TAL 2,511,935

TRAVELING GRATE sToxER INCLUDING CRATE BAR RETAINING mms 6 Sheets-Sheet 5 Filed Jan.' 31, 1946 r mx.. w, Vc@ m N o AL mr .n Y B June 20, 1950 E L, M|DGETTE ErAL 2,511,935

TRAVELING GRATE STOKER INCLUDING GRTE BAR RETAINING MEANS Filed Jan. 51, 1946 6 ShBBtP-Sheet 5 patented `une O,

'rRAvELING GRATE s'roKER, INCLUDING GRATE BAR RETAINING MEANS..v

Ernst L. Miagette, Philadelphia, Pa., anaune Beck, Lyndhurst, N. J., assignors to American Engineering Company Philadelphia, Paj., a, 09g; A

poration of Pennsylvania e Application January 31, 1946, Serial No. `($44,580

3 claims. (clj. v11o-44o) This invention relates to stokers, and more particularly to traveling grate stokers employed in spreader type furnaces.

One object of the present invention is to provid a simplied and generally improved stoker of the traveling grate type.

Another object is to provide a simplified and highly improved operating mechanism for the traveling grates of stakers of the character de'- scribed p A still further object is to provide in traveling grate stokers improved means for preventing separation of the grate bars as they pass over one of the sprocket wheels or drums.

Other and further objects .will become apparent as the description of the invention progresses.

Of the drawings:

Fig. 1 is a front elevational view of the furnace vcomprising the present invention, showing the fuel hoppers, the fuel conveying and feeding mechanism, and the operating mechanism for the grate associated therewith.

Fig. 2 is a side elevational view, diagrammatic in part, of the operating mechanism for the grate, certain of the elements of which are shown in section to illustrate the principle of operation thereof.

Fig. 3 is a longitudinal sectional view taken throughout the furnace showing the stoker and the fuel feeding mechanism associated therewith.

Fig. 4 is a sectional view taken substantially along line 4-4 of Fig. 3.

Fig. 5 is an end elevational view taken substantially along line 5-5 of Fig. 3.

Fig. 6 is a sectional view taken substantially along line 6-6 of Fig. 3.

Fig. 7 is an end view, partly in section, taken substantially along line 'I--l of Fig. 3, some of the grate bars having been removed to show the structure of the sprocket wheels and shaft.

Fig. 8 is a view of the undersides of the upper sealing plates provided near the front end of the stoker lshowing the mechanism for holding them in operative position.

Fig. 9 is an enlarged fragmentary sectional view of the sealing means provided at the rearwardly disposed end of the stoker and of the grate bars adjacent thereto.

Fig. 10 is a sectional view taken on the line I0-l0, Fig. 11.

Fig. 11 is a sectional plan View taken substantially along line II-II of Fig. 10.

Fig. 12 is a plan view of one of the grate bars of the traveling grate.

Fig. 13 is a sectional view of the grate bar shown in Fig. 12, taken substantially along line I3.-LI3 of Figf12.v "j' Fig. 14 is an end view of kthe grate bar shown in Fig. 12,

Fig. 15 is a sectional view of the grate'vbar takenjsubstantially along line I5-I5 of Fig.12. Fig. 16 is a sectional view taken substantially along line I B-IB of Fig. .12., Fig. 17 is a sectionalfview taken substantially along line II-I'l of'Fig. 12; and

Fig. 18 is a perspective view of a segmental sleeveffor retaining-the grate bars in position on 'their respective pins. 1

Referring to the drawings, the numeral I indi.- cates generally a furnace having frontand rear walls 2 and 3, respectively, and side walls 4 and4 5. The grate 6 oflaustoker I ofthe traveling grate type is, mounted in `the furnace l and forms the bottom wall thereof. Mounted at spaced points on the outer surfaceh of front 4wall 2 are a pair of coal' hoppers 9 and' Ill.v Fuel from hoppers 9 and III gravtates ontotraveling conveyors II and I2, respectively, whichl in turn convey the said fuel to feeding and spreading rotors I3 and I4. The rotors I3 and I4 aresecured to a shaft I5 and are driven by an electric motor I6 through any suitable variable speed transmission indicatedgenerally at I1. 'Ihefuelwconveyors II and I2 are .operatively connected `to shaft I5 byV belt and pulley connections I8 and I9, respectively. The fuelwconveyors II land I2 and the rotors I3 and Il maybe of any suitable construction, and since the specific structure thereof forms no parto'f the present invention a detailed descriptionv of vthese devices will not be given. For a full disclosure of such fuel conveyors reference may be Vhadv to the UnitedStates vpatent to GeorgewW. Olney, No. 2,099,618, granted on November v16, 1937. For a full disclosure of rotors of the type shownl herein reference may be had to the pending application of Ernst L. Midgette and Robert W. Reid, Serial'No. 599,812, filed on June 16, 1945.

As shown more particularly in Fig. 3, fuel "from conveyor II is delivered to rotor I3 which 'in turn feeds itthrough an opening 20 provided 'parts may be employed without departing from the invention.

The front end of the grate 6 extends into an ash receiving extension 24 of the furnace, comprisingha metallic enclosure having a tcp wall 25, end Wlal1s52p6 and21, and a front wall 28.

The lower end of front wall '2 terminates va short distance above the grate 6, thereby providing a space 29 therebetween which extends across the entire width of the furnace. The front wall 28 of extension 24 has provided therein three spaced rectangular openings in substantial alignment with the space 29 between Vthe grate --6 and the lower end of front wall 2. These openings are normally closed by hinged furnacedoors 30, 3| and 32, respectively. Normally closed observation openings 33 and Mare-also provided, respectively, at the opposite ends of front ,wall28 in substantial alignment with the space 29 above the grate.6. Access to the stoker may,.according ly, be had to remove clinkers or vashes `from. the grate or tocorrect any condition inthe fuel bed that may require attention.

As shown more particularly in Fig. .4, the grate 6 is comprised of three lsections 36, 31 and 3S disposed transversely of the Stoker. It is apparent, however, that a greater or lesser number of sections may be provided, depending upon the Width of the furnace, without departing from the invention. Each of the grate sections 36, 31 and .38, as shown more particularly in Figs. 3 and 6, comprises a series of overlapping grate bars 39. The grate bars 39 of .each .section are, as hereinafter more fully described, pivotally attached at widely spaced points to apair of chains 40, 40. The chains 4 0, 40 for each section are trained .over a, pair of rear sprocket wheels 4|, 4| and ,a corresponding pair of front sprocket wheels 42, 42.` The sprocket wheels 4| for all the sections are secured to a shaft 43 mounted in suitable Ybearings 43a and 43b provided inthe closing plates vi246 and 24| disposed adjacent side walls 4 and l5, respectively, of the furnace. Intermediate bearings 43 and 43d' secured .to the rearwardly disposed ends of .beams |30 and |29, respectively, are also provided for .shaft 43. The sprocket `wheels 42 for all thesections are similarly se- `cured to a shaft 44 mounted in bearings 44a and 4,4h provided respectively inthe side walls 26 and .2.1 of extension 24. vIntermediate bearings 4.4c `and 44d secured to the front ends of vbeams* |29 and |30, respectively, are also provided for shaft 44.

.Shaft 44 is drivenby anbperating mechanism zindicated ygenerally .at .41, Aand vthrough the con.- nections just described operates the grate 6 from `rear -to front of the furnace. -A considerableporltion of the fuel fed tothe furnace by the rotors i3 and |4 is burned in suspension. The remainder ,of the fuel is burnedon the grate `6 as it travels toward the front of the furnace. The ashes are dumped over the front end of thegrate 6 as the `grate bars 39 thereof pass around the front sprockets 42 and gravitate into an ash hopper 48 disposed beneath the extension 24, from which -they may be removed from time to time by rany suitable means. Air under pressure is supplied to 4the chamber 49 beneath the grate 6 through an opening 49a provided -in side wall 5 and side closing plate 24| by any suitable fan or blower mechanism (not shown).

Referring to Figs. 1 and 2, the operating mechanism 41 for the grate-I6 Acomprises .a ratchet wheel 50 secured to the outer end of shaft 44 adjacent bearing 45. Loosely mounted on shaft 4 44 and disposed at either side of ratchet whe'ei 5o are a pair of multi-armed operating plates 5|, 5|. Plates 5|, 5| are held in spaced relation in any suitable manner, such as by shouldered bolts 52. A pawl 53 pivotally mounted on a pin 64 secured in aligned apertures provided in the arms 55, 55 of plates-5|, 5| engagesvthe ratchet wheel i50. Pawl 53 has a weight 56 adjustably secured thereto for holding it in engagement with the ratchet wheel when the plates 5|, 5| are moved in onedirection and for allowing the pawl to ride over the teeth of the ratchet wheel when the plates 5|, 5| are moved in the opposite direction.

` The plates 5|, 5| are oscillated, in the embodiment illustrated, by means of a fluid motor 51 pivotally supported on a pin 58 mounted at the upper end of a bracket 59 which in turn is secured to the floor of the boiler room, in any suitable manner. Fluid motor 51 comprises a casing 6.0 having a piston 6| operating therein. The upper end of the pistonrod62 secured topiston 6| is ypivotally attached to a pin 6,3 secured in aligned apertures provided in the arms 64, 64 of plates 5|, 5|. Thus upon movement ofthe piston 6| upwardly, a clockwise movement is imparted to plates 5|, `5|, causing the pawl 53 to actuate the ratchet wheel 56, and,jconsequently, the shaft 44 in a clockwise direction and thereby effecting a movement of the upper run of the grate 6toward the front of the furnace. Upon a downward movement of the piston 6| the plates '5|, 5| are moved in a counter-clockwise direction during which time the pawl 53simply rides over the teeth of ratchet wheel5l and, consequently, no retrograde movement is imparted to the said ratchet wheel or to the grate 6.

Fluid motor 51 is operated by a pump 65 driven by an velectric motor 66. 3Pump65 may be of any suitable "type, such for example as a variable discharge, radial piston type of pump, shown and described in the United States patentl to Henry .S. Hele-Shaw .and Francis L. Martineau, No. 1,077,979, granted `on November 11, 1913, and to which reference may be had for a full disclosure thereof. The direction of operation of fluid motor 51 is controlled by a four-way control valve'61, which in turn is controlled by a trip valve 68. Valves 61 and 63 may be secured to the end wall 26 of extension '64 by boltsor by any other suitable securing means.

During operation thereof fluid from a makeup tank 69 is drawn into pump 65 through a pipe 1|] andis discharged therefrom through a pipe 1|. Pipe 1| is connected to the inlet port 12 of valve 61 and .by a branch pipe .13 to the inlet port 14 of valve `68. The `outlet lports 15 and 16 of valve.68 are connected to the ports 11 and 18, respectively, provided at the opposite ends 0i' valve 61 by pipes 1,9 land 83. A fourth port 8| of valve 68 is connected '.to makeup tank 69 by a pipe 82. A rotatable-valve element 8.3 is provided in the casing of valve 68 and ,has secured thereto apair of laterally extending lugs 34 and .85 adapt- -ed to be Vengaged by dogs 86 and .81, respectively .adjustably mounted on a bar 88 which in turn is secured to the arms 89, 89 of plates ,5|, 5|. Valve element 83 has a slot or passage 96 provided around a portion of the periphery thereof which, whenfthe -valve elementis rocked in a clockwise direction by .engagement tof .lug by dog .81,

lvconnects .ports J5 with por-t 1-4, thereby causing fluid from pump 65 to enter the .port .11 -of valve 61 through pipe 19. When rValve element 33 is rocked in a counterclockwise direction by engagement .of lug 84 by dog 86, port 16 isconnected to inlet port 14, thereby causingfiuid from .pump

65 to enter port 18 of valve 61 throughpipe 80. Valve `element 83 has an'additional portor passage 9| provided therein which is adapted to connect port; 15 with exhaust port 8| when passage 90 connects ports 14 and 16.to pressure, and to connect port 16 to exhaust port 8| when passage 90 connects ports 14 and 15 to pressure.

Valve 61 comprises a cylindrical casing 94 having-apair of spaced valve elements. 95 and 96 mounted in the cylindrical interior |05 thereof. Valve elements 95 and 96 are'secured in spaced relation on a stem 91, the opposite endsof'which extend through aligned apertures provided in the end plates 98 and 99 of valve 61. Valveelements 95 and 96 normally close a pair of ports |00,` and |I| Aprovided at the upper end of thefcasing 94. Port |is connected to the upper end of the cylinder 60 of uid motor 51 by means of a pipe |02. 4Port |0|, on the other hand, is connected to'the'lower end of cylinder 60 of motor 51 by means of a pipe |03. Casing 94 is provided with a passage |04 at the lower end thereof which is connected to the opposite ends of cylindrical chamber by ports |06 and |01. A port |08 is provided at the lower end of casing 94 and extends from the outer wall thereof to passage |04. A pipe |09 connects port |08 todrain pipe 82 which in turn is connected to make up tank 69. End plates 98 and 99 have enlarged cylinders ||0 and l respectively, provided therein which communicate with the ports 11 and 18, respectively, provided at the outer ends thereof. a

As shown in Fig. 2, a branch pipe I I2 connects pipe 1| with the inlet port ||3 of an adjustable relief valve |4. Relief valve ||4 is of usual construction and the discharge port ||5 thereof is connected to drain pipe 82 by .a pipe |I6.

From the foregoing description it is seen that when the parts are in the position shown in Fig. 2 dog 81 has engaged lug 85 of valve 68, causing shifting .of the valve element 83 thereof so as to cause fluid from pump 65 to enterport 11 o f valve 61 through pipes 1| and 13, port 14, passage 90, port 15, and pipe 19. The fluid Pressure act-` ing on the end of valve stem 91 causes movement of the latter and, consequently, of valve elements 95 and 96 to the right, thereby connecting the chamber |05 of casing 94with port |0|. Fluid from pump 65 now flows through pipe 1| vinlet port` 12, port |0 and then to the lower end of cylinder 60 of fluid motor v51 through pipe |l3 to cause the piston 6| to move upwardly. Upon movement of valve elements 95 and 96 to the right, r

as aforesaid, the fluid in chamber displaced by the end of connecting rod 91 ows to makeup tank 69 through port 18, pipe 80, port 16 of valve 68, passage 9|, port 8| and pipe 82. It is also seen that as piston 6| moves upwardly the uid at thev upper end of cylinder 60 of fluid motor 51 will ow to makeup tank 69 through pipe |02, port |00, chamber |05, port |06, passage |04, port |08, pipe |09, .and drain pipe 82. Upon movement of piston 6I of uid motor 51 upwardly the operating plates 5|, 5| aremoved in a clockwise direction, thereby causing the pawl 53 carried thereby to operate the ratchet wheel 50 in a clockwise direction to effect a movement of grate 6 of stoker 1 toward the front of the stoker. 1 Als plates 5|, 5| approach the limit of their travel dog 86 engages lug 84 of valve 68, causing movement of the valve element 83 thereof in a counter-clockwise direction, thereby causing passage ,90 to, connect ports 14 and 16 to pressure and passage 9| to connect ports 15 and 8| to exhaust. Fluid from pump 65 now enters port 18 of valve 61 through pipes 1| and 13, port 14, passage'90, port..16 vandpipe 80, causingxshifting of the valveelements 95and 96 to the left and ,there` by connecting port |001with the interior of charm ber |05;l The'uid displaced by the end of valve stem 91 `in cylinder. I|0 ilows to exhaust through port 11, pipe .19, port 15, passage 9|, port 8| and drain pipe 82. Fluid from pump 65 now nows to the upper endof Vcylinder 60 of fluid motor 5.1 through pipe1l,I port 12, port |00 and pipe` |02,v thereby causing piston 6|A to move` downwardly.- Fluid at the lower. end of cylinder 60 nownows to makeup tank 69 through pipe |03, port |0.|, chamberv |05, port,|01, passage |04, port |08, pipe |09 and drain pipe 82. When the piston 6| ap` proaches its lower limit of travel, dog 81 will again engagelug 85 to shift valve elements 83 to the. position shown in Fig. 2, thereby effecting a reversal of flow U4of fluid to motor 51 and again causingthefpiston 6| operatingA therein to move upwardly, as previously described. In this manner the upper run of grate 6 is caused to move by increments toward the front of the Stoker. The stroke of the piston 6| may be varied by adjusting the dogs 86 and 81 on rod 88. To reduce the stroke, the dogs are brought toward each other; and vice versa, to increase the stroke, the dogs are moved away from each other. 1 f The speed of operation of motor 51 and, conse-. quently, ofthe grate 6 may be varied by simply varying the volumetric discharge of pump 65 in a well-known manner. l

` Referring more particularly to Figs. 1 and 4, it will be observed that the grate bars 39 of the sections 36, 31 and 38 are slidably supported upon skid plates |24, |25, |26 and |21 which are se.. cured in any suitable m-anner to supporting beamsv |28, |29, |30 and |3|, respectively. Skid plates. |24, |25, |26 and |21 and their supporting beams4 |26, |29, |38 and |3| extend substantially the en tire distance between front and rear sprockets 42: and 4|, respectively, and in turn are supported'. upon a series oftransverse beams |32 mounted. on any suitable supports |33 provided on the side: closing plates 240 and 24|.

' The chamber 49 beneath the stoker is closed at the rearwardly disposed end thereof'by means of' a closing plate |34 extending transversely of the Stoker between side closing plates 240 and 24|. A curved plate |35 is secured to the upper edge of closing plate |34 and extends around a portionV of the Arearwardly ldisposed end of the grate 6, as shown i'nligj.` 1.l The plates |34 and |35 may be made up in'secti'ons, if itis: so desired. The front end of plate |35 i's'formed with a rearwardly extending tongue |36'which, 'as shown more clearly in Fig. 9, 'engages `a corresponding forwardly extending tongue |31 formed at the rearwardly disposed ends of therear sealing plates |38. The sealingplates |38 are v'disposed in end to end` relation yacross', the Stoker, and each consists of a flat upper portion |39I which terminates in a downwardly curved portion |40 at the frontend thereofand a fiat rearwardly extending portion |4|. In` order to assemble the sealing plates |38 on the Stoker, the tongues|36 and |31 are simply interlocked and the plates then assume the posi#` tion shown inFigs. ly and 9, with the flat portions'L |4 thereof resting'upon the grate bars 39. a Inasmuchas the grate bars 39,:or'10vev toward the front of the stoker during operation thereof, the sealing,L lzylates,` |38 yalso ...tend `to moveA inf: that direction,

thereby niaintiningithe interlocking engagement f'theplates |35'and |38.

The rear wall 3 has mounted in cooling relationzthe'rewit-h-a series of fluid conducting tubes |42. These tmbesv are secured' at their lower en'ds' in a transverse header |43 mounted'on a' supporting beam |44 spaced a short distance to the-rear of the-Stoker 1. The tubesv |42 extend forwardly, as shown at |45, and overlie the plates |35 and |38 and are then bent upwardly, as shown at |45, and.. form the exposed portion ofthe': rear wall 3 of the furnace. Asrv shown inLFig. 1, a sealing .plate |46 pivotally'attafched to` the;` lower ends of the tubes |42 rests upon the upper. surface of plate |35. The sealing plateL |46 may be made up in sections or several platesdisposed in end to endrelation andmay beem'ployed if itis so desired; Heat resistive packing material- |41-` may beplaced between the lower portionsofthe tubes |42=and th'eup# per; surface of plate |35 and in contact-.withiplate |46 to i-preventV the' escape of 'gasesVv from4 the fur.'-` nace. Suitable heat resistive packing material |'48imay alsov be placed at therearward-ly. disposed sides of the tubes |42 and aroundthe header'. |43 to further seal the wallagainstthe leakage of furnace gases.A f

Mounted'. transverselyl of the stoker 1'` and. 'disposedl in spaced relation near the.A rearwardlydisposed end of the` ash receiving extension 24 areV alp'air. of channel beams I5!!k and |5|; A skidirarnp |521for. the grate 6 is securedtothe upper flanges of beams |501 and and comprises an upper flat inclined portion |53, `a pair of spaced supporting legs |54 and..|55, and spaceditransverse webs |56` and.- |5,1.

As shown in Fig. 1, the legs |54 and. |55 are supported: upon the beams |50. and |5|, and. the webs |56 and |51 form extensionsy of the said beams AI fallend.V |5| and in effect provideseals to prevent the leakage of air from the chamber 49. Theskid ramp |52 `may extend across the entire-width of the Stoker or it may be made upvin sections disposed in end to end relation, as desired. Spaced upwardly from the skid ramp |52. is a sealing plate |58. Sealing. plate ,|58` comprises an inclinedsubstantially flat -lower portionr |59 disposed in substantially parallel relation with the inclined upper portion |53of skid ramp |52 Vand a pairwpf slightly inclined vertically extending webs |66 and |6|`. Sealing-A plate |59 is not positively secured to the framework but simply floats upon the grate barswdisf posedtherebeneath. The webs |60 and [6| overlap Athe sides of the lower ilange of supporting .beam |32-, the web I|| during operating periods 'lying in abutting relation with said arge and forming therewith a seal toprevent'theescape of air between the portion of the grate disposed 'between the ramp |52' 'and sealing plate |58fan'd 4the upper flange of the forwardly disposed supporting. beam |32. The forward edge "|58" of jplate |58 lis rounded, as' shown in' Fig. v3, ,tol

prevent interference with the grate b'ars 39 :as they pass between the said plate'158" and skid ramp |52.

Extending forwardly from` the forward vedge' vof the upper flange'of the forwardly disposed ,supporting beam |32 are a series'of sealing plates' |62.'H These plates, as shown'rn'ore particularly :in Fig; 6, extend between and are securedin' any" vsuitable'manner, such as by bolts, to'su'p- -portingbrackets |63 'extending laterally'o'f beams of skim-plates? |24',` |25.; '|26 and |21-, near-the forwardy endsthereof' and in engagement with the udersides" offthe grate bars 391 f each 0f the-sections 36; 31? and 38, is an upper sealing plate. -|65.' Each sealingV plate |65, as shown nore'- particularly in Figs.v 3. 6 and 8, isl of; substantially rectangular construction and4 fhas a downwardly extending flange |66 provided Aat either sidey thereof which in assembly. lie 4infsubff stantially abuttingl relation with the sideedges ofL associated -skid plates. A transverseprib or web-` |61 depends from theV underside of each plateV` |65'intermediate the front and rear edges' thereof? which iri assembly overlaps andf lies in juxtapsition with the rearwardly disposed yside offtheassocia'ted vertical'sealingplate |62.' Renfor'eing'ribs |68fand |69 are also'provided o'n the underside of Veach sealingplate |65. To-vprevent -interferencewith the grate bars 39 during operation: of the latter, each sealing plate fis bent"downwardly at the front and rear-.edges thereof, as shown at |10 and |1'|, respectively, inFig 3'.- As-shown more particularly in Fig. `8, the underside of each sealing'v plate |65 ispro. vided" with a'pair of spaced flat bearingA surf-aces |12., |12; In assembly each bearingl surface |12 isengaged by one end |13 of* an associat'e'd'leverv |1'4pi'votall'y mun'ted'o'n a ro'd' |15. The" other e'rid1 |16 of v eachlever 14 is provided with arnotclfi. or hookl |11 for receivinga ring provided' at 'the' upperffenfd of awe'ight supporting rod |18.- A se'r'i'e's 'off weights-|19 are mounted on eaehl rod- |18? and are held'thereo'n by a nut |80 engaglf ing the lower threaded e'ndofsaid rod. The lrodsl |`|5flareI supported inl'any suitable bearing brackets |8'I -seured to' andv extending laterally off supporting beams' |28, |29, |30 andV |31. It',- tllerefre,"A is se'nf' thatv the Weights |195 acting on the levens 14' urg'e the' sealing plates 165mm engagement with the' undersides of the grate bars '39. The side flanges |66 lying in abutting rel-ation with the side edges of skid plates |24?, |25, |26 andr |-21 prevent a-ir leakage therebee. tween. It f'is also seen th'atbecause of the over# lappingrelation of the ribs |61 and plates |62;v the iii the chamber beneath-the stoke'r is pre 'rited ffrom escaping-therebetween. The seal-1 regnare mi, tfensversebeam |325, senin'g plate |53(`sfkid"-raip |52l and beams |50 and l5l'alsb eifee't'ively 'seal ther chamber beneath the stel-rerl against' air-leakage.v In'asmuch -as the grate bars 39 completely' occupyy thespace between skid ramp'v F52 and sealingpla'te |58, they effect' alsl forrriaJ-sealfag'ainst air leakage between "the said'ramp |52andpl'ate1 |58.

yvferring more-'particularlyto Figs. 10't'o--18ij each; grate bar'39 comprises an elongated bodyl portion |83 haring a onrvedfu'p'per fuel-support# ingipernonl'aa and en'd'wans las and iss: Trie dirvatnre 'fb'dfy portion |83'at the 'top'th'efe'fii's'f "latively'gradual, as-shown at |81, and bel-1 edy es-sharpr'as iti-'approaches the bottom edge dicated at |89. The side wa11sVl485-'and prdviydee'with notches@ |85@ and latere-f. spect'ivly, 'fatA the fo'ut'er forwardly disposedsids: meteor-ane with-notches lesb and lash at their" inner irealrwardlyffdisposed* sides. These notches inf-*assembly permit" the forward vportions of sl'd'ef walls I 85 and-"|86 ofi-each grateY bar 33th' overlap? the rearwardly d'i'sposedprtior'is of theside'wails I'lijari'd |'6`6ffrs'pectively of the next" forward grat-'atar o these-'ries as shawn 'more pained-f larly in- Figs: 10 -and -1l; A v'Il'ie-lffrntedge v| 91 of'bod'y portion l`8`3'ispro vide'dw'itlifa serie'sfof slots orrecesses 9-'2thro'gl 9 which draft air may pass; The gradually curved portion- |81 of each grate bar 39 also has a series of" apertures |93` and |94 provided thereinxfand arranged in staggered' relation, as shown in Fig. l2. *The front wall of each recess- |92 'is inclined, as shown at |95, so as to direct the air upwardly and rearwardly over the curved surface |81 of the next grate bar of the series to the rear thereof. The vrear wall |96 Vof each ofthe apertures 94 is also inclined so as to direct the air upwardly and forwardly over the'next grate bar in advance thereof. as shown by the arrows in Fig. 10, whichnot only intensifies the burning rate of the fuel supported on thev grate but also distributes it over theentlre area thereof. The apertures |93 disposed between the recesses |92 and apertures |94 direct the air more or less upwardly. As a result ofthe construction and arrangement ofthe air` openings just described, draft air is directed over the 'entire area' of the grate6. I

Each grate bar 39 has depending from As shown more particularly in Figs. 10, 12 and` 13, the portion `of the body portion |83 of each grate bar 39disposed between the pairs of ribs |91, |91 and.|98, |98 is cutaway so as to form substantially rectangular openfrecesses 293, 293

therebetween for receivingV the operating chains 49. Reenforcing ribs 204, 295, 296, 291 and 298 extend respectively between side wall. |85 and` rib |91, ribs |91, |9'|,'ribs |91 and |98, ribs |98, |98 and rib |98 and side wall |86. Rib 295 is cutaway, as shown at 299 and 2|0, and rib A291 is likewise cutaway, as Shown at 2| land 2 2, to provide clearance for the links of the chains 49 as the grates pass around the sprocket wheels 4| and 42. The body portion |83 is also cutaway, as shown at 2|3 and 2|4, to accommodate the chains 49.

As shown more particularly in Figs. and 11, chain 49 is of usualvconstruction and consists of a series of links 2|5 connected by the pins 20|.

Each of the slots 299, 209 provided in ribs |98,`

|98 comprises an'upper semicircular portion `2|6 having a radius substantially equal to'that of aipinv 29| and an enlarged portion 2|1 for receiving the locking sleeve 292. The slots |99 and 200 are open at the lower ends to permit entry of pins 29|. The opposite ends of pins 20| extend beyond the outer sides of ribs |98, |98 and are provided with annular recesses 2|8 and 2|9 -for receiving split spring locking rings 229 and-22|, respectively. vThe slots |99, |99 provided infribs |91, |91 are similar to the slots 290, 299 and also receive the pins 20| of the associated chain 40 and the locking sleeves 202.`

,To attach the grate bars 39 to the associated chains 49, the pins 20| are urged into the upper portions of the slots |99, |99 and 299, 29|). The sleeves262 are then inserted into'the lower portions of the slots and snugly fit the undersides of the pins. The locking rings then are inserted in the annular recesses provided at the ends of the pins 29|. The sleeves 292 are held against 4axial movement by the links 2 l5 of chains 40 at one end thereof and by the locking rings at the other end. The grate bars 39 are thus pivotally supported on the pins 20|.

Inasmuch as the pins 20| engage the grate bars 39 beneath the center lines thereof, the rear edges A- crossflow'of air, accordingly, resultsv the im-' derside of the body portion |83 thereof two pairs |9| of the said grate bars are urged into and maintained in contact with the curved upper surfaces of the next adjacent grate bars of the series, as shown in Figs. 1 and 10. The grate bars 39 remain in contactv until they move past the skid ramp |52 when they swing about their pivots, as shown in Fig. 1. Any ashes clinging to the grate bars 39 thus are removed by gravity before they pass around the rearsprocket wheels 4|.

In order to prevent separation of the grate bars 39 until they pass around a substantial portion of the front sprocket wheels 42, a series of shoes 223, 224, 225 `and 226 are provided. As shown in Figs. land 5, the shoes 223, 224, 225, and 226 are pivotally supported intermediate their ends to the upper ends of supporting arms 221, 228, 229 and 239, respectively, which arms in turn are secured at their lower ends to a transversely extending rod 23|. Rod 23| is secured in any suitable manner against axial and rotary movement in brackets 232 secured to and extending forwardly of the web f|51 of skid rampl |52. The inner faces 233 (Fig. 3) of shoes 223, 224, 225 and 226 are arcuate and conform with the curvature of the grate bars 39 as they pass around the front sprocket wheels 42. The shoes 223, 224, 225 and 226 are of sufcient length to extend around a group of grate bars 39. Themiddle shoes 224 and 225 engage the grate bars 39 of sections 36, 31 and 31, 38, respectively, near the adjacent ends thereof. )The end shoes 223 and 226 prevent spreading of the outer-ends of the grate bars 39 of sections 36 and 38. Inasmuch as the shoes 223, 224, 225 and`226 extend around a group of grate bars 39 and are pivoted intermediate their ends, they are self-adjusting and thus effectively retain the grate bars in contact while they pass around the front sprocket wheels 42, even though irregularitiesexist Vin the individual grate bars.

Referring more particularly to Fig. 4, it will be observed that the skid plates |24, |25, |26 and |21 have -longitudinally extending recesses 235, 236, 231 and 238, respectively, provided therein. The upper surfaces ofthe skid plates |24, |25,

|26 and |21 are smoothand support the lower.

edgesY |88 of the grate bars 39. The adjacent ends of the grate bars 39of the sections 36, 31 and 38 are spaced slightly apart and Overlie the recesses 236 and 231. *Air from the chamber 49, accordingly, flows aroundthe inner sides of end walls |85 and |86 of the grate bars39 and into the recesses 236 and 231, respectively, and then through the spaces between the adjacent ends of the grate bars, as shown'by the arrows in Fig. 14, to effect'burning of the fuel lying between the grate sections. Y

`The end walls |85 and |86, respectively, of the grate bars 39 of sections 36 and 38 are spaced slightly from the upper ends of side closing plates 240 and 24|. A'ir from chamber 49, accordingly, flows over the upper surfaces of end skid plates |24 and |21 and aroundthe inner surfaces of end walls |845 and |86 of the grate bars 39 of sections 36 and 38, respectively, and into recesses 235 andA 238, and thence through the spaces between the ends of saidgrate bars and the side closing plates240 and 24| respectively, as shown 1 by the arrows` in Fig. 4, `to "effect burning of the fuel lying in these regions of the fuel bed.

a Simpued anefh-ienlyximnroved stekerfhasfbeen provided; The rotors, laandl Ht propel the fuel through the openings 0l-1 provided; in. the; front Walk?, of; the furnace and sprealdyit over-the grateY 6r, as shownbyl dottedslirges; in Fig,-v3. As previ;-

ously pointed out, alarge portion ogft-he fuelisv burnedi in suspension-, while the; remain-den is. burned on the1 grate; as.; it; moyed j iroxnfrear tofront; oir the furnaceV by the. operating mechanism,A indicated at, 41:, Alg for combustion is admitted-I to. tnefuel: bed tlireilell-l 'ehe-- Openings:a |32@ |f93fand |194-f0f the grate barsf39- and; tlriroughy the clearance spaces between; the,- adiaeent ends; of the grate hars and betweenthefendsv` off the; grate bars anda the side: elesine; plates; 2M and-- 2st-l', as previouslydeserbedr, The frent and-rearsealing@` plates, |65 and |38; preyentihe: draf-t, air from passing throng-h1thel g-rate bars3,3 beyond thelinner. edgesoiqsaid sealing -platgesjl Air leakagefrom the chamber? 4S; beneaththe` stoken is.y prevented; at@ the, reen:` thereof by,c close. ine' plate: Iihcurvedgnlatef L35@ Sealinernlates |46 andx packing` material" Milt at the Sides by; Side: closing-plates 24e; anda 2.41 :1 and atsthe freut. ba Supporting beams: Illl andi Ili. the: Skidf ramp |52, the-.grateiloarsf 3,8;the.:Sealing@plateA |58; the fronte supportingI bea-m;v |325 andi sealing( plates. I62-3and1` |65.

The shoesfiZZ, 22.417125: and; 22,6,.may:engagev thei grateY bars:` 39 i in15erInediti-te-z the. endsofthe latter, ifa is4` sa desired.. '1T-hef.' structure;- Qf.. the sealing-.f plates, grate.- bars'. and operating-mechanism may also be,Variedctobestcsuitfthe Operatel ing conditions of: a particular installation without. departing from thednVenti/Qn,

Accordingly,4 While the;4 embodiments o f the inf.

vention, hereinshown,a'nddteeribed,A is admirably' 4 adapted tofull-lllk the. Objects, prfnnarilystated, it isto be understoodthat, isgnotintendedto lim-it the.y invention;theretoslnoe t; may beemV bodied in other iorxnsg all comingA Withinr` the. scope of the-claims whilnfollow.

What is claimed is:

1. A furnace-stokencomprising a; flexible .end IeSSLtra-Yelna grate consisting ef. en liepen fuel` supporting run-,anchv alowerfreturn run, saidgrate,

temprising-afseriesef:snbstantallr parallel grate. f'

bars disposed in overlapping relation,operating` chainsffer'saidferate, meanssfer; pivetally attaching the. said eratefbarsito. Said. chains, Shaft. rotatably mounted; adiaaentthe freut end, Gisele.

eratera SecondiShaftmeuntedladiacentthe. rear-- 69,

vtardly disposed; end.w 0i; Said grate, Sprockets ferr Said; chains: secured, tefsaid Shafts. meansv forl operating'one ofsaidgshafts :to eifect-a -mpyement of `the upper-run ofsaid` grate from,rear -to front of. saidstokenjandmeansfor retaining theV said grate bars-in contact with adjacent grate bars.. asthey pass around, the; sprockets on saidfront shaft, `said last mentioned means comprising one or more` shoes, l a ,transversasupport a, standar-d for, each; of, said shoes, V means,forl securing` said Standardste Said transversesnppqrtand means for;pivota1ly,connectingsaid shoes to said stand;- arde-4 122 2: Afurnace: Stoker comprising a, plurality'fof'- exible..endlessitravelingrgrates disposed in side,l by. siderrelation, each of' said gratesv consisting; or anA upperY fuel; supporting I run and alower return;

run, eac-hi ofsaid'v g-ratescomprising av series Qi,x

substantially parallel grate bars d isposedin overlapping relation, operating chains for said grates. means=forlpivotally attaching the said: grate barsz tm said chains', ashaftirotatably mounted adjaf.

lill centtheront end on saidgrates; a second shaft rotatably mounted; adjacent the= rearwardly diss.. posed: endoffsaidfgrates, sprockets for said chains;I secured: tosaid shafts, means for operating; one:- of' said"V shafts: to` effeotfa movement of' the upper.I

@i runs: off said; gratesv from rear.v tov front off saidv Stoker, and means. for; retaining said grate bars in\ contaotwith adjacent grate*l bars as. they pass. around. thesprocketslon saidr front shaft; saidz lastfzmentioned means-{comprisinga yseries offY are.

ouate shoes, at leas-t one for engaging the grate bars of each of said grates, a nom-rotatablerodl asupporting. arm fory eachv of. said: shoes, means yfor securing saidrarms to said: rod, andmeans for pivotally supporting said shoes: onsaidarms at..

points intermediate: the ends. off' said. shoes.

3.- A, furnace-Stoker comprising a flexible end'- less traveling grate, saidv gratey consisting ofv a.. series of substantially parallelfgratebars'disposed in overlappingrelation, connectingr meansA forV 30. saidi grate bars, means-for pivotallyconnecting saidL grate-bars toA saidi connecting' means, rotateable means-for operating saidzgrate, and means disposed1 adjacent said rota-table means. for.r re. taining'said grate. bars incontact with-each othera asl they.` pass? around: said rotatable means, sad,

REFERENCES i ermu- The following references are of recordfln. the leof` this patent:

STATESTPATENTS 

